Warning: Major spoilers ahead

Late at night, the Marathon Man pulls up to a gas station dressed all in black. Looking on edge, he buys boxes of Mac and Cheese but gets distracted at the register when he sees a news bulletin with Carrie’s face on it. When he gets back in the car, Milo, whose hair is now dyed brown is in the back seat, complaining that he’s tired.

When the man promises to get him to bed, he asks if it was his “real bed or his vacation bed”. He tells Milo his vacation bed, but they need to do something together really quickly without Carrie, as she needs to hide because she’s famous. Milo asks if he’s famous and he says no.

The next morning, while in bed with his wife Casey, Alcaras discusses how best to look after their non-verbal son, Sam. She’s been looking at St Marks, a special facility for those with his diagnosis, where he’ll have carers who can cater to his needs, as well as other children in the same position. But with only one reduced tuition spot available, it feels like a lottery for their son’s future. She says she’d do anything to get him in.

As they get ready for work and have breakfast, Alcaras shares what’s been going on as they enter day four of Milo’s disappearance. He’s hesitant to release the picture, knowing that once they do, he’ll be aware the police are looking for him and may do something to Milo. She asks him if he’s worried he’ll be violent, to which Alcaras says “even good people can do bad things if they’re pushed.”

With Casey heading off to work at the hospital, Alcaras is left in charge of getting Sam ready for the day. The pair sing and dance together while getting dressed, before he receives a text regarding new information.

Giving Sam a packet of Skittles, as he likes to split the colours apart, he calls Jenny and asks if he can show Jacob the photo he has of the Marathon Man, hoping he may have met him while under Carrie’s care. Unfortunately, Jacob has no idea who he is.

He then receives a call from Marissa, who has the same reasons for being hesitant about making the man’s picture public, but he reassures her that it’s the best thing to do. As Alcaras drops Sam off for the day, he looks on lovingly at his son, as other SEN children play around him in a notably underfunded public school.

A week earlier, Alcaras received a call from someone on the St Mark’s school board. While Sam still wasn’t approved, the man informs him it could swing in his favour if he’s able to make arrest charges for the associate dean’s son go away. The kid was arrested for ‘possession of a controlled substance’ which Alcaras deduces must be Xanax, as rich kids always steal their parents’ meds.

Alcaras tells him it’ll be expunged from his record after a year, but with the son applying to colleges he doesn’t have the time. Alcaras furiously tells him that he’s “not that guy” and thinks it’s disgusting that a privileged man with the ability to fund a dozen kids is making those without money scrap over one spot and has the nerve to ask him for a favour.

However, it seems over the course of the last few days, he may be having a change of heart.

As he heads back to his car, he sees a report showing the photo of the Marathon Man has been released, with the news cycle abuzz once more.

At the office, Alcaras is updated on the car forensics, revealing multiple fingerprints were found in Carrie’s recovered vehicle, and no leads from the Marathon Man – that is, until Esther, the woman whose address was used on the day Milo was kidnapped, comes to the station and identifies him as Kyle Smith, who she at one point fostered for a year before he aged out the system.

She explains his mother died from an oxy overdose when he was a teen, but when he was with her he had got his GED, and while he was skittish, he was kind. She lost touch with him in the years since, noting the last she heard he had been arrested for selling oxycontin, and had been in jail for six years. She says she doesn’t believe he would be involved in a kidnapping, Alcaras has to tell her that unfortunately that can’t be the case – seeing as it can’t be a coincidence Marissa was sent to her home.

With a massive new lead, the team gets to work trying to track him down. They discover his only visitor in prison was Carrie Finch, a week before his release, at a time when she was already working for Jenny’s family.

Heading down to the prison, Alcarez and Grecco speak to his cellmate, who says Kyle was quiet, and thought the visitor was a sister or cousin, as he was quiet after she visited. The cellmate theorises he would be in South Shore, his old neighbourhood, as that might be all he has left. They thank him and leave, promising to bring the boy home.

Outside the prison, the pair piece together the information they have to find a drywalling business in South Shore that could be where he worked. While everyone refuses to talk, they decide to wait to try and catch a worker on the bus on the way home. They spot a woman and try to get her to talk, asking if she knows Carrie Finch. While she says no, it doesn’t matter – they got a hit on Kyle renting out a white Toyota Camri.

As the woman sits on the bus, she searches up Carrie’s name, and after seeing the photo says to herself that it’s “Josie”.

Over at the Irvines’ house, Alcaras drops in to update Marissa on what’s going on. He notices that Milo was “creative with colours”, often using the wrong ones to colour in fruit and to follow along with spelling.

Showing her a picture of Kyle, he shares that the likely motivation behind the crime was financial as the family has no connection with the family. He asks again if they’ve been sent a ransom demand, saying he understands the desire to follow their instructions without police input, but it would be a wrong move. She assures him that she’s received nothing.

Over tea, Marissa asks him about Sam, and he tells her he’s 13 but has disabilities. Sharing a photo, she asks if he worries about him. He gives a contrived answer and changes the subject, asking if Peter would have got the ransom message. She says although he likes to take charge, he wouldn’t keep something that big from her.

When Alcaras asks why Peter likes to take care of people so much, she tells him she doesn’t know, it’s just how he’s always been. She shares about Brian’s accident – noting Lia was four, Brian six and Peter 10 – saying Lia was playing and hyperactive when Brian fell. While it was an accident, she believes Lia’s had it on her conscience ever since.

Alcaras shares that he worries about Sam getting sick and not being able to tell them, or what would happen when they’re gone and can’t look after him. However, he also takes joy in Sam not being able to understand, because then he wouldn’t be so happy-go-lucky and hug him as much. Marissa says if or when Milo gets back, she will make sure nothing bad ever happens to him again, because you do anything for your kids.

Finally, Alcaras shares that Esther was Kyle’s foster mother and believes he sent Marissa to her for a reason – noting that, aware she would be having the worst day of her life, he made sure Marissa was sent to the kindest person he knew.

When Alcaras picks Sam up from school, the teacher praises him for being so well behaved, which makes him happy. But as he gives his son a hug, it quickly turns to sadness when he realises that Sam’s diaper had not been changed, as he’d been left alone for at least two hours playing. He does it himself before driving him home.

That evening, when he goes home, he takes a Tylenol bottle from the bathroom cabinet, deciding to switch the pills in the evidence locker after all so Sam gets the school he needs. He heads to the station and gets the job done, before fretting about it in bed.

However, he has little time to worry when he gets a call, saying they got the biggest lead yet – CCTV from the gas station. Realising he bought mac and cheese for a stove, they realise he’d need to be in a house as motels would only have microwaves. They head over to some nearby lakehouse rentals to ask questions, where one woman claims to have potentially seen her. However, she adds that she’d already left, having paid in advance.

When they look at the house, they spot weird stains on the floor, and a small bit of blood spatter on a cabinet. They immediately call forensics and a search team to see if they can find a body in the lake, and as he waits Alcaras hears from Casey that Sam got into St Marks. But his happy moment is ruined as an officer informs them they’ve found a body.